1. Field of the Invention
This invention relates to coke oven emission control apparatus and to the method of operating such apparatus, and more particularly to apparatus for and methods of capturing and controlling particulate and gaseous emissions produced during the production of coke in and the pushing of coke from a battery of coal coking ovens.
2. Description of the Prior Art
The production of coke has always presented serious air pollution problems. Polluting emissions escape during all phases of the coking operation, from the charging of coal into the hot ovens, through the coking process, during pushing of coke from the ovens into quench cars for cooling, and during transportation in the quench cars to the quenching station. The major portion of metallurgic coke used today is produced in recovery type ovens which are operated at a slight positive internal pressure and as a result there is a tendency for the hot, gaseous distillation products or fumes to escape, particularly around the oven doors which are extremely difficult to seal. The incomplete combustion of such escaping fumes in the atmosphere results in substantial particulate and gaseous pollutants in the atmosphere.
As incandescent coke is pushed from an oven through a coke guide into a waiting quench car, the coke mass breaks up in the atmosphere. As the incandescent coke breaks, violent burning takes place and large volumes of high temperature gases are quickly released. The rapidly generated and expanding gases carry substantial volumes of particulate matter into the atmosphere. This burning continues, although at a somewhat reduced rate, in the quench car until the coke is cooled or quenched, conventionally in a quench tower constructed adjacent one end of the oven battery.
The numerous prior art enclosures for controlling cokeside emissions have not been entirely satisfactory for various reasons. For example, the early coke side sheds were generally constructed with relatively small internal volume so that substantial emission leakage occured as a result of the rapid expansion of gases during pushing. Further, the relatively heavy, heat resistant structures were generally supported at least in part on the oven structure, placing undesirable loads on the ovens which are, of necessity, operated under extremely high temperature conditions. Attempts to withdraw pushing emissions uniformly along the full length of the shed have similarly resulted in the escape to substantial quantities of polluting emissions in the vicinity of the quench car. To overcome this problem attempts have been made to direct the entire exhaust to the area of the oven being pushed, or into the area of the quench car as it is moved along the ovens. However, these attempts have not been entirely satisfactory, and also failed to adequately control fugitive emissions during coking, or have required operation of excessive exhaust equipment, and a consequent waste of energy, during periods when ovens were not being pushed.
U.S. Pat. No. 3,630,852 discloses a shed structure enclosing the coke side of an oven battery, with the roof of the shed resting on the endwall of the battery and with an exhaust pipe leading from one endwall of the shed into the quenching tower to permit the escape of emissions from the shed into the tower beneath a water spray. This coke side shed has not proved satisfactory in that all emissions were forced to flow from the closed shed through one outlet in the endwall of the shed. Further, supporting the shed roof on the oven wall places substantial loads on both the shed and the oven structure as a result of thermal growth and contraction of the two structures.
U.S. Pat. No. 3,844,901 discloses a coke side shed which projects substantially above the oven battery and has an enlarged cross section at its top to provide increased capacity for emissions. An exhaust duct extending the full length of the shed at its top, has spaced air scoops to meter the flow of emissions into the duct in such a manner as to provide a uniform pressure within the duct along the full length of the shed. However, the generation of large volumes of emissions at one point within the shed during pushing of an oven could result in spilling of the emissions around the bottom edge of the sidewall of the shed before such emissions could distribute themselves for withdrawal along the full length of the shed in the enlarged top portion.
U.S. Pat. No. 3,937,656 discloses the coke side shed in which the major portion of the weight of the roof structure is supported, in cantilevered fashion, from a vertical girder spaced outboard of the quench car tracks. The rigid structure is, nevertheless, secured to the endwall of the ovens so that thermal expansion and contraction of the oven structure could place substantial load on this support. An exhaust pipe is provided for removing the emissions from the shed, and an inlet 17 can be automatically regulated by a control element, presumably a valve.
U.S. Pat. No. 3,879,267 discloses a coke side shed structure for controlling emissions, and contains a statement that, in an alternate arrangement, the shed roof is designed so that it is supported solely by the wall of the shed remote from the battery. The manner in which this is accomplished is not described.
U.S. Pat. No. 4,053,366 discloses a coke side emission control shed structure which includes an exhaust duct 26 mounted outside of and extending along the shed, with a plurality of branch pipes connected between the primary exhaust duct and the exhaust shed at spaced intervals. Remotely controlled valves in the branch pipes are operated to open only those valves above a car containing hot coke either during pushing or during transport to the quenching tower. This main exhaust system is used only to control quenching emissions, and a separate exhaust system is provided to remove fugitive emissions escaping from the doors during the coking operation.
U.S. Pat. No. 3,716,457 discloses a coke side shed structure having a plurality of partition walls positioned above the quench car track, and an elongated vertical movable wall mounted on the coke guide is adapted to cooperate with the partition walls to form an enclosed compartment above a quench car during the pushing operation. A main exhaust duct extends outside the shed and a plurality of short pipes opening one into each compartment are connected to the main exhaust duct to remove emissions from the respective chambers. Valves are provided in the branch pipes. The coke shed is spaced from the oven battery and emissions are confined only when the quench car is adjacent the coke guide. No means are provided for withdrawing fugitive emissions by the exhaust system.
U.S. Pat. No. 3,746,626 discloses a coke side emission control system including a shed having an exhaust duct extending along its roof and having a plurality of valve-controlled inlets from the shed into the exhaust duct at spaced intervals along its length. The valves are opened and closed by the quench car moving along the tracts to direct the exhaust to those inlets above the quench car. Baffle walls in the shed are intended to confine the emissions to the area of the quench car.